Modular System for Transporting Wind Turbine Blades

ABSTRACT

A modular system for transporting wind turbine blades in at least two different spatial arrangements comprising two or more root end transport frames having a height H for supporting the root end, wherein H&lt;D (D=bolt circle diameter), and two or more first tip end transport frames having a height H1 for supporting the blade towards the tip end, each first tip end transport frame has a base frame and a support bracket provided on top of the base frame, wherein each first tip end transport frame is stackable on top of a root end transport frame and vice versa, so the system is operable to stack successive blades in an alternating root end to tip end arrangement. The first tip end transport frame is replaceable with a second end transport frame that increase the inter-blade spacing, or with a tip end or a root end distance piece.

FIELD OF THE INVENTION

The present invention relates to a modular system for transporting windturbine blades and to a use of the system for providing a suitablespatial arrangement of at least two wind turbine blades for transport.The present invention also relates to a transport system fortransporting wind turbine blades in at least two different spatialarrangements.

BACKGROUND OF THE INVENTION

Wind turbine blades used for horizontal axis wind turbines forgenerating electrical power from wind can be rather large and may exceed70 metres in length and 4 metres in width. The blades are typically madefrom a fibre-reinforced polymer material and comprise an upwind shellpart and a downwind shell part. Due to the size and fragility of theselarge rotor blades, the blades may be damaged during transport as wellas during loading and unloading. Such damages may seriously degrade theperformance of the blades. Therefore, the blades need to be carefullypackaged in order to ensure that they are not damaged.

However, due to the increasing length of modern wind turbine blades, itis gradually becoming more complicated and expensive to transport theblades. It is not uncommon that the transportation costs amount to 20percent of the total costs for manufacturing, transporting and mountingthe wind turbine blade on the rotor of a wind turbine blade. Also, someblades are transported to the erection site through different modes oftransport, such as by truck, train and ship. Some of these modes oftransports may have restrictions on large loads, maximum heights,maximum widths, maximum distances between transport frames or supports,for instance dictated by local regulations. Therefore, there exists alogistic problem of providing transport solutions that are suitable forvarious types of transport.

Overall, there is a demand for making transport solutions simpler, saferand cheaper. In particular, there is a demand for making such systemsmore flexible such that adaption to a certain transportation situationis possible. This applies for example for shifting from land transportto sea transport. While height restrictions require lowest possibleinter-blade spacings, sea transport may require an increased inter-bladespacing to avoid contact between blades during sea disturbance. Theprior art shows various solutions for transporting more than one rotorblade using a single container or other packaging system, which is anobvious way to reduce the transport costs. However, the afore-mentionedrestrictions and limits may increase the difficulty of transporting aplurality of blades using the same packaging system.

WO 2014/064247 describes a transportation and storage system for atleast two wind turbine blades. The system is adapted to stack the bladesin an alternating root end to tip end arrangement. The tip end of thesecond wind turbine blade may extend beyond the root end of the firstwind turbine blade, and the tip end of the first wind turbine blade mayextend beyond the root end of the second wind turbine blade, when thefirst and the second wind turbine blades are arranged in the packagingsystem.

EP1387802 discloses a method and system for transporting two straightwind turbine blades, where the root end of a first blade is arranged ina first package frame, and the tip end of a second, neighbouring bladeis arranged in a second package frame that is arranged next to andconnected to the first package frame with the effect that the blades arestored compactly alongside each other in a “tip-to-root” arrangement.However, in this transport system the tip end frames support the bladesat the very tip of the blades, where they are mechanically most fragile.Further, the package frames are arranged at the root end face and theblade tip. Therefore, the distance between the package frames areapproximately equal to the length of the blades. For very long blades of45 metres or longer, this might not be possible due to local regulationsand restrictions on transport.

It is therefore an object of the invention to obtain a new method andsystem for storing and transporting a plurality of wind turbine blades,which overcome or ameliorate at least one of the disadvantages of theprior art or which provide a useful alternative.

Particularly, it is an object of the invention to provide a moreflexible transport solution that is able to accommodate for differenttransport situations and regulatory requirements.

SUMMARY OF THE INVENTION

In a first aspect, the present invention relates to a modular system fortransporting wind turbine blades in at least two different spatialarrangements, each blade having a tip end and a root end, each bladefurther having a bolt circle diameter D at said root end, the systemcomprising two or more root end transport frames each having a height Hfor supporting a root end of a wind turbine blade, wherein H<D, two ormore first tip end transport frames each having a height h1 forsupporting a portion of a wind turbine blade towards the tip end of saidblade, each first tip end transport frame comprising a base frame and asupport bracket provided on top of said base frame for receiving aportion of a wind turbine blade, wherein each first tip end transportframe is stackable on top of a root end transport frame and vice versa,such that the modular system is operable to stack successive windturbine blades in an alternating root end to tip end arrangement, andwherein the modular system further comprises at least one of parts (i),(ii) and (iii):

-   -   (i) two or more second tip end transport frames each having a        height h2 exceeding h1 for supporting a portion of a wind        turbine blade towards the tip end of said blade, each second tip        end transport frame comprising a base frame and a support        bracket provided on top of said base frame for receiving a        portion of a wind turbine blade; wherein each second tip end        transport frame is stackable on top of a root end transport        frame and vice versa to replace the first tip end transport        frames, such that the modular system is operable to stack        successive wind turbine blades in an alternating root end to tip        end arrangement with two alternative inter-blade spacings        resulting from the respective use of either the first or the        second tip end transport frames;    -   (ii) two or more tip end distance pieces each attachable on top        of or below a first tip end transport frame, wherein the first        tip end transport frame and attached tip end distance piece is        stackable on top of the root end transport frame and vice versa,        such that the modular system is operable to stack successive        wind turbine blades in an alternating root end to tip end        arrangement with two alternative inter-blade spacings resulting        from the respective use of the first tip end transport frames        either with or without the tip end distance pieces; and    -   (iii) at least one root end distance piece having a height h3        and being attachable in between two vertically stacked root end        transport frames, wherein (H+h3)≥D, such that the modular system        is operable to stack successive wind turbine blades in a root        end to root end arrangement as alternative to the root end to        tip end arrangement by stacking two or more first or second tip        end transport frames at one end and two or more root end        transport frames with interposed root end distance pieces at the        opposing end.

It has been found that such modular system is inexpensive and offers ahigh degree of flexibility allowing for transport of two or more windturbine blades in various spatial arrangements. For example, landtransport in a stacked root end to tip end arrangement may be carriedout with a minimum inter-blade spacing to minimise height of the overallstack by using the root end transport frames together with a set offirst tip end transport frames having a height h1. When the freight isreloaded for subsequent sea transport a stacked root end to tip endarrangement with an increased inter-blade spacing and an increasedoverall stack height may be accomplished by replacing the first tip endtransport frames with the second tip end frames of part (i) having aheight h2 which exceeds h1. Reducing overall height is not as much of aconcern in sea transport as compared to road transport. Instead, seatransport is potentially more turbulent which necessitates higherinter-blade spacings. A similar effect is obtained when using the tipend distance pieces of part (ii).

Typically, the increased height h2 will be provided by an increased baseframe height of each second tip end transport frame as compared to thefirst tip end transport frames.

While the invention has been described as increasing the height bychanging to a new tip end frame having an increased height or using tipend distance piece to increase the inter-blade spacing, it is alsorecognised that a corresponding technical effect may be achieved byinstead changing to a tip end frame having a lower height or providingthe tip end frame with a removable tip end distance piece.

In one spatial arrangement a first wind turbine blade may be placed suchthat the tip end of the first wind turbine blade points in a firstdirection, and a second wind turbine blade is placed such that the tipend of the second wind turbine blade points in a second direction, whichis substantially opposite to the first direction. The tip end of thesecond wind turbine blade may extend beyond the root end of the firstwind turbine blade, and the tip end of the first wind turbine blade mayextend beyond the root end of the second wind turbine blade, when thefirst and the second wind turbine blades are vertically stacked in thisarrangement. It is thus apparent that the system is adapted to arrangingthe first and the second wind turbine blades substantially parallel toeach other and pointing tip to root but with an overhang.

The downside of such an arrangement is the increased overall length ofthe stack. The modular system of the present invention may also addressthis problem by providing an alternative spatial arrangement. Using part(iii), a root end to root end stack can be provided by arranging theroot end distance piece in between two root end transport frames stackedvertically. Thus, the overall length of the stack is reduced in anefficient and simple manner.

Typically, the frames are arranged such that a root end transport frameand at least a portion of a successively-stacked tip end transport framewill overlap with the root end diameter of a wind turbine bladesupported by the said root end transport frame, and wherein the tip endtransport frame is arranged such that a tip end of a supported pre-bentor swept blade will be spaced from the ground.

Preferably, the modular system comprises part (i). In anotherembodiment, the modular system comprises part (ii). In yet anotherembodiment, the modular system comprises part (iii). The modular systemmay also comprise two of parts (i)-(iii), such as parts (i) and (ii),parts (i) and (iii), or parts (ii) and (iii). In another embodiment, themodular system comprises all three of parts (i), (ii) and (iii).

Preferably, the wind turbine blades are stacked vertically. In oneembodiment (H+h3) is within 0.95 to 1.05 times h2; most preferably(H+h3) equals h2. In such embodiments, at root end to root end stack canbe provided by using stacked root end transport frames with interposedroot end extension pieces at one end and second tip end transport framesat the opposing end without substantially changing the tilt of the windturbine stack as compared to the root end to tip end stack.

In a preferred embodiment of the modular system, h1 is less than 0.9times h2. Advantageously, h1 is less than 0.8 times, preferably lessthan 0.7 times, more preferably less than 0.6 times, and most preferablyless than 0.5 times h2.

In another embodiment of the modular system, (H+h3) is at least 1.05times D, such as at least 1.1 times D, at least 1.15 times D, at least1.2 times D or at least 1.25 times D.

In another embodiment of the modular system, (0.5 D)<H<(0.9 D),preferably (0.5 D) <H<(0.75 D).

In another embodiment of the modular system, each root end transportframe has a height, a width, and a depth, wherein the width of said rootend transport frame is equal to or greater than the bolt circle diameterof a wind turbine blade to be supported by said root end transportframe.

In another embodiment of the modular system each root end transportframe has a height, a width, and a depth, wherein the depth of said rootend transport frame is equal to or greater than one quarter of the widthof the root end transport frame.

In another embodiment of the modular system each root end transportframe comprises: a frame body and a root end plate coupled to said framebody, said root end plate arranged to couple with a root end of a windturbine blade, wherein said root end plate is arranged to couple withless than ⅔ of the bolt circle of a root end of a wind turbine blade tosupport said wind turbine blade on said root end transport frame.

In another embodiment of the modular system said root end platecomprises a substantially C-shaped body arranged to couple with aportion of the bolt circle of a root end of a wind turbine blade.

In another embodiment of the modular system each root end transportframe comprises: a frame body and a root end plate for coupling to theroot end of a wind turbine blade, wherein said root end plate ishingedly coupled to said frame body.

In another embodiment of the modular system said root end plate ishingedly coupled to the frame body of said root end transport framealong the horizontal axis.

In another embodiment of the modular system said root end plate ishingedly coupled to the frame body of said root end transport framealong the vertical axis.

In another embodiment of the modular system said root end plate ismounted on at least one bracket arm, said at least one arm coupled tosaid root end transport frame via a hinged joint.

In another embodiment of the modular system said at least one bracketarm comprises an articulated bracket.

In another embodiment of the modular system said root end transportframe comprises at least a first and a second bracket arm, wherein saidfirst and second bracket arms are positioned on opposed sides of anotional central longitudinal axis of a wind turbine blade to be mountedto said root end plate.

In another embodiment of the modular system said first and second tipend transport frames each comprise a frame body, at least one tip endsupport bracket for supporting a portion of a wind turbine blade towardsthe tip end of said blade, wherein a first end of said tip end supportbracket is hingedly coupled to said tip end transport frame along thehorizontal axis, and wherein a leading edge support lip is provided onsaid bracket, said leading edge support lip arranged to receive aportion of the leading edge of a wind turbine blade supported by saidsupport bracket, such that the wind turbine blade can be pivotably movedabout said hinged coupling relative to said tip end transport framewhile supported on said bracket.

In another embodiment of the modular system a second end of said supportbracket may be releasably secured to the respective frame bodies of saidfirst and second tip end transport frames when said support bracket isreceived in said frame body.

In another embodiment of the modular system said tip end support bracketcomprises a flexible strap having a support surface provided on saidflexible strap.

In another embodiment of the modular system the first and second tip endtransport frames further comprises a securing strap to be fitted arounda wind turbine blade received in said tip end transport frame.

In another embodiment of the modular system said first and second tipend transport frames are arranged to be positioned at a location towardthe tip end of a wind turbine blade to be supported by the modularsystem, such that a sweep or bend of the wind turbine blade from thelocation of said tip end transport frame to the tip end of the supportedblade is less than respective heights of the base frame of the first andsecond tip end transport frames.

In another embodiment of the modular system a wind turbine blade to besupported by the modular system has a longitudinal length L, and whereinthe first and second tip end transport frames are arranged to bepositioned at a distance F from the root end of said blade, wherein (0.5L)<F<(0.95 L), preferably (0.6 L)<F<(0.85 L).

In another aspect, the present invention relates to the use of themodular system of the present invention for providing a suitable spatialarrangement of at least two wind turbine blades for transport, eachblade having a tip end and a root end, by selecting among:

-   -   a) an alternating root end to tip end stack with a first        inter-blade spacing using at least two root end transport frames        and at least two first tip end transport frames, such that the        tip end of the first wind turbine blade points in a first        direction and the tip end of the second wind turbine blade        points in the opposite direction;    -   b) an alternating root end to tip end stack with a second        inter-blade spacing exceeding the first inter-blade spacing        using at least two root end transport frames and at least two        second tip end transport frames, such that the tip end of the        first wind turbine blade points in a first direction and the tip        end of the second wind turbine blade points in the opposite        direction;    -   c) an alternating root end to tip end stack using at least two        root end transport frames and at least two first tip end        transport frames, wherein a tip end distance piece is attached        on top of or below each tip end transport frame, such that the        tip end of the first wind turbine blade points in a first        direction and the tip end of the second wind turbine blade        points in the opposite direction;    -   d) a root end to root end stack using at least two root end        transport frames and at least two first or second tip end        transport frames, wherein a root end distance piece is attached        in between two vertically stacked root end transport frames,        such that the tip end of the first wind turbine blade points in        the same direction as the tip end of the second wind turbine        blade.

Preferably, the first inter-blade spacing is less than 0.9 times thesecond inter-blade spacing, such as less than 0.8 times or less than 0.7times the second inter-blade spacing. With a variety of possible shapes,curved surfaces and stacking arrangements, the inter-blade spacing willtypically vary over the length of the blades even within a single stack.As used herein, the term “inter-blade spacing” refers to the minimumvertical spacing in between two vertically stacked wind turbine blades.

In yet another aspect, the present invention relates to a transportsystem for transporting wind turbine blades in at least two differentspatial arrangements, each blade having a tip end and a root end, eachblade further having a bolt circle diameter D at said root end, thesystem comprising: two or more root end transport frames each having aheight H for supporting a root end of a wind turbine blade, wherein H<D;two or more extendible tip end transport frames for supporting a portionof a wind turbine blade towards the tip end of said blade, eachextendible tip end transport frame comprising a base frame, at least onevertical extension means for extending the height of the tip endtransport frame and a support bracket provided on top of said base framefor receiving a portion of a wind turbine blade; wherein each extendibletip end transport frame is stackable on top of a root end transportframe and vice versa, such that the modular system is operable to stacksuccessive wind turbine blades in an alternating root end to tip endarrangement with at least two alternative inter-blade spacings createdby varying the height of the extendible tip end transport frames via thevertical extension means.

Such transport system offers the advantage of providing flexibility intransport situations that require different inter-blade spacings, suchas land transport versus sea transport. By extending the height of thetip end transport frames by using the vertical extension means anincreased inter-blade spacing can be achieved in an efficient, simpleand cost-effective manner.

Preferably, the vertical extension means are suitable for extending theheight of the tip end transport frame stagelessly.

In a preferred embodiment, the vertical extension means increase theoverall height of the tip end transport frames by at least 5%, morepreferred at least 10%, and most preferred at least 20%. It will beunderstood that the vertical extension means is an integral part of theextendible tip end transport frames. Accordingly, the overall height ofthe frame may be made up of the height of the base frame, the supportbracket and the height of the extension means extending beyond the baseframe.

In a preferred embodiment of the transport system, the verticalextension means consists of one or more threaded legs suitable forcontinuous height adjustment and at least partially received in the baseframe of the extendible tip end transport frame.

Such legs may suitably comprise an outer thread, which is received in afixture comprising a bore with a matching internal thread within thebase frame of the extendible tip end transport frame.

In other embodiments, the extension means may comprise extendibleelements which form part of the base frame, e.g. telescopic postsprovided in each corner of the base frame. In these embodiments, theheight of the base frame as such may be increased by the verticalextension means.

Alternatively, a support portion for supporting the tip end of the blademay be movable within the tip end frame, such that the inter-bladespacing may be varied by varying the position of said support portion.

A typical method for transporting or storing at least two wind turbineblades using the modular system or the transport system of the presentinvention comprises the steps of: a) placing the first wind turbineblade so that the tip end of the first wind turbine blade points in afirst direction, b) placing the second wind turbine blade adjacent andin immediate vicinity to the first wind turbine blade so that the tipend of the second wind turbine blade points in a second direction, whichis substantially opposite to the first direction. Typically, the secondwind turbine blade is in step b) arranged so that the tip end of thesecond wind turbine blade extends beyond the root end of the first windturbine blade. The tip end of the first wind turbine blade may alsoextend beyond the root end of the second wind turbine blade. This willinevitably be the case, if the first wind turbine blade and the secondwind turbine blade are of the same length.

Thus, two wind turbine blades may be arranged substantially parallel toeach other and oriented in opposite directions. Since the thickness ofthe blades is typically decreasing from the root end towards the tipend, the blades can with the new “tip-to-root” layout be arranged on topof each other via frames having a relatively small combinedcross-section.

According to an advantageous embodiment, the first wind turbine bladeand the second wind turbine blade in steps a) and b) are stacked on topof each other, i.e. so that the second wind turbine blade is arrangedabove the first wind turbine blade. Advantageously, the first windturbine blade and the second wind turbine blade are arranged so thatchordal planes of their respective tip ends are arranged substantiallyhorizontally. By “substantially horizontally” is meant that the chordalplane may vary up to +/−25 degrees to horizontal.

In a preferred embodiment, the blades are arranged so that an upwindside (or pressure side) of the blade is facing substantially downwards.

In a stacking system for storing more than two blades, it is alsopossible to stack the blades both horizontally and vertically, i.e. in astacked array.

Typically, the wind turbine blades will have a length of at least 40metres, or at least 45 metres, or even at least 50 metres. The bladesmay be prebent so that, when mounted on an upwind configured horizontalwind turbine in a non-loaded state, they will curve forward out of therotor plane so that the tip to tower clearance is increased.

The first and the second wind turbine blades may be prebent. Suchprebent blades may be arranged in the tip end frames and root end framesso that they are straightened slightly or fully during transport, e.g.as shown in WO05005286 by the present applicant. However, the bladesneed not forcedly be straightened. Since the blades are supported nearthe ends and the blades are arranged with the upwind side facingdownwards, the own weight of the blade may straighten the blades due tothe gravitational forces acting on the middle part of the blade.

According to a preferred embodiment, the root end of the first windturbine blade is arranged in a first root end frame, the root end of thesecond wind turbine blade is arranged in a second root end frame, thetip end of the first wind turbine blade is arranged in a first tip endframe, and the tip end of the second wind turbine blade is arranged in asecond tip end frame.

The tip end frames typically comprise a receptacle for supporting a tipend section. Thus, the first tip end frame comprises a first tip endreceptacle, and the second tip end frame comprises a second tip endreceptacle. Depending on the particular solution, the receptacle may forinstance either support the pressure side of the blade or alternativelythe leading edge of the blade. However, in principle the receptacle mayalso support the suction side of the blade or even the trailing edge ofthe blade. The frames themselves may be used as lifting tools so thattwo or more blades may be lifted in one go and without imposing stressto the blades.

In a typical embodiment of the modular system, one first tip end framewith a height h1 is connected, optionally detachably connected, to aroot end frame, and another first tip end frame with a height h1 isconnected, optionally detachably connected, to another root end frame.After replacing the first tip end frames with the second tip end framesto increase inter-blade spacing, one second tip end frame with a heighth2 is connected, optionally detachably connected, to a root end frame,and another second tip end frame with a height h2 is connected,optionally detachably connected, to another root end frame.

In another embodiment of the modular system, one first tip end framewith a height h1 is connected, optionally detachably connected, to aroot end frame, and another first tip end frame with a height h1 isconnected, optionally detachably connected, to another root end frame.Inter-blade spacing may then be increased by attaching the respectivetip end distance piece to each first tip end frame.

In yet another embodiment of the modular system, one first tip end framewith a height h1 is connected, optionally detachably connected, to aroot end frame, and another first tip end frame with a height h1 isconnected, optionally detachably connected, to another root end frame.To decrease stack length both root end frames are attached on top ofeach other separated by the root end distance piece with a height h3.The respective root ends of the blade are received in the respectiveroot end frames. Likewise the two first tip end frames are stacked ontop of each other on the opposite side to receive the respective tipends of the blades.

Preferably, the connection parts of the root end frames and the tip endframes that connect to or fix the blade in the frame may be hinged tothe frame itself. This can for instance for the root be achieved byconnecting a plate to the root of the blade that is hingedly connectedto the frame. Similarly, this can be achieved by letting a tip endreceptacle be hingedly connected to the tip end frame. Such embodimentshave the advantage of alleviating loads that would otherwise beintroduced to either the frames or blades due to blade deflections orthe like during transport.

In another advantageous embodiment, each root end frame is a root endbracket adapted to be attached to a root end face of a wind turbineblade. This provides a particularly simple solution, where the frame orbracket may be attached to for instance a root end plate of the bladeand without having to support the exterior of the blade. Thus, externaldamages to the outer surface of the blades may more easily be avoided.The tip end frames (with receptacles) may be attached to the brackets,so that the tip end extends beyond the bracket, when the blade isinserted into the tip end frame (and receptacle).

In yet another advantageous embodiment, the connection between root endand tip end frames is an L-shaped or a T-shaped configuration so that abase of the L- or T-shaped configuration is attached to the root end ofthe first wind turbine blade, and a transversely extending frame part(or extremity) of the L- or T-shaped configuration supports alongitudinal section of the tip end of the second wind turbine blade.Advantageously, the L- or T-shaped configuration is formed so that thebase is a root end face bracket attached to the root end face of thefirst blade, and the transversely extending frame part supports a tipend section of the second blade.

Advantageously, the frame connection is arranged so that the base of theL- or T-configuration is arranged vertically. The transversely extendingframe part may be arranged to that it extends from the top or the bottomof the base. In this configuration the second wind turbine blade isarranged on top of the first wind turbine blade. The extremity ortransversely extending frame part may thus support either a part of thesuction side or the pressure side of the blade in an upwardly facingreceptacle. Alternatively, the extremity may extend from the side of thebase. In such a configuration, the blades are arranged side-by-side, andthe extremity or transversely extending frame part may support either apart of the leading edge or the trailing edge of the blade in anupwardly facing receptacle.

If the blades are arranged so that both blades are facing with theleading edge downwards (in the side-by-side arrangement) or with theupwind shell parts facing downwards (in the vertically stackedarrangement), it is clear that the transversely extending frame parts ofthe two frame assemblies must be arranged inversely compared to the baseframe. Thus, the two frame assemblies have slightly differentconfigurations.

The L- or T-shaped frame assembly has the advantage that thetransversely extending frame supports a larger part of the tip sections,thus better alleviating loads and possibly also minimising the necessaryoverhang of the tip part that extends beyond the root end frame.

In one embodiment, the longitudinal extent of the transversely extendingframe part is at least 1 meter, advantageously at least 1.5 metres, moreadvantageously at least 2 metres. The longitudinal section of the tipend of the blade may be supported along the entire section, or it may besupported in a plurality of discrete sections within the extremity ofthe L- or T-shaped frame assembly.

As an alternative to the L- or T-shaped frame assembly, the root endframe and the tip end frame may be arranged substantially in the sameplane.

Advantageously, a plurality of first wind turbine blades and second windturbine blades are placed in an array, and wherein the wind turbineblades each comprise a shoulder defining a maximum chord of the blade,and wherein the blades are arranged so that the maximum chord forms anangle of between 20 and 75 degrees to a horizontal plane, advantageouslybetween 22 and 73 degrees. Even more advantageously, the maximum chordforms an angle of between 15 and 35 degrees to a horizontal plane,advantageously between 20 and 30 degrees. It is clear that this stackingmethod may be advantageous to any configuration of stacking blades sideby side with the root end and tip end arranged in the same direction. Ina preferred embodiment, it is the root end of the blade that is turnedbetween 15 and 35 degrees to a horizontal plane, advantageously between20 and 30 degrees. The angle may for instance be defined by bond linesbetween an upwind shell part and a downwind shell part at the root endof the blade. In this setup, the blades in a stacked array may bearranged so that they slightly overlap with the shoulder of one bladeextending partly over an adjacent blade, so that the upwind side of oneblade near the shoulder faces down towards the downwind side near theleading edge of an adjacent blade. Thereby, it is possible to stack theblades in frames having a width corresponding to the diameter of theroot or only slightly larger, even though the chord length of theshoulder exceeds this diameter.

In another embodiment, intermediate protection members are arrangedbetween the first wind turbine blade and the second wind turbine blade.Advantageously, the intermediate protection members are arranged nearthe tip end frames so as to provide additional support to a tip endsection of the wind turbine blade. The protection means prevent theblades from being damaged due to bending or the blades impacting eachother. The intermediate protection members are particularlyadvantageous, when the blades are stacked on top of each other. In sucha setup, the intermediate protection members may be used as support forsupporting an additional tip end section of one blade and may transferloads from the tip end of the upper blade to the mechanically strongerroot region of the lower blade. Additional protection members may bearranged below the lowermost blade in a stacked array and a supportplatform or the ground. The additional protection member isadvantageously arranged to support an additional tip end section of thelowermost blade, e.g. near the tip end frame of the lowermost blade.This is particular relevant for embodiment, where the inter-bladespacing is low, thus being particular applicable to embodiments for landtransport and storage.

The intermediate protection members may be made of a foamed polymer.

In another embodiment, a root end face of the first wind turbine bladeis arranged within 45 metres of a root end face of the second windturbine blade, advantageously within 42 metres. Accordingly, root endbrackets or frames should also be arranged at maximum 45 metres or 42metres from each other.

Typically, one first tip end frame may be connected, optionallydetachably connected, to one root end frame, and another first tip endframe may be connected, optionally detachably connected, to another rootend frame.

In one advantageous embodiment, the root end frames are root endbrackets adapted to be attached to a root end face of a first windturbine blade and a second wind turbine blade, respectively. Thisprovides a particularly simple solution, where the frame or bracket maybe attached to for instance a root end plate of the blade and withouthaving to support the exterior of the blade. Thus, external damages tothe outer surface may more easily be avoided. The first or second tipend frames or the extendible tip end frames (with receptacles) may beattached to the brackets, so that the tip end extends beyond thebracket, when the blade is inserted into the respective tip end frame(and receptacle).

Typically, the tip end of the first wind turbine blade, when arranged inits tip end frame, extends a first longitudinal extent beyond the tipend frame, and the tip end of the second wind turbine blade, whenarranged in its tip end frame, extends a second longitudinal extentbeyond the tip end frame. In other words, the tip end frames are adaptedto package the tip end of a wind blade at a first distance from the tip.The distances will typically be approximately the same. The firstlongitudinal extent and the second longitudinal extent may be at least 2metres, advantageously at least 3.5 metres, and more advantageously, atleast 5 metres. The blade tip may even extend at least 6, 7, or 8 metresbeyond the tip end frame.

In a particular advantageous embodiment, the modular system or thetransport system is adapted to stack the first and the second windturbine blade on top of each other. One tip end frame may for instancebe attached to a top of one root end frame, and another tip end frame isattached to a bottom of another root end frame. In this setup the bladesare arranged so that chord planes of the tip ends of the blades arearranged substantially horizontally. The setup may be adapted to arrangethe blades with an upwind shell part substantially downwards.

In another embodiment, at least a first intermediate protective memberis arranged between the first wind turbine blade and the second windturbine blade. The first intermediate protective member mayadvantageously be arranged near the tip end of an upper arranged bladeof the first wind turbine blade and the second wind turbine blade.Additionally, a second protective member may be arranged below the lowerof the two wind turbine blades. In a stacked array, this blade will thenalso be an intermediate protective member arranged between two blades.Further, a protective member may be arranged below the lowermost bladein the stacked array. The intermediate protective members may be made ofa foamed polymer.

It is clear that some of the provided solution may also be used forother configurations of transporting and storing blades, e.g. withoutthe tip overhang.

A typical method for transporting or storing at least two wind turbineblades with the modular system or the transport system of the presentinvention comprises the steps of:

-   -   a) placing the root end of a first wind turbine blade in a root        end frame,    -   b) placing a tip end section of the first wind turbine blade in        a tip end frame,    -   c) placing the root end of the second wind turbine blade in        another root end frame,    -   d) placing a tip end section of the second wind turbine blade in        another tip end frame, wherein    -   the root end frame of step a) and the tip end frame of step d)        as well as the tip end frame of step b) and the root end frame        of step c) are connected as L-shaped or T-shaped frame        assemblies so that bases of the frame assemblies are attached to        the root ends of the first and the second wind turbine blade,        and extremities of the frame assemblies support a longitudinal        section of the tip ends of the first and the second wind turbine        blades.

Advantageously, the first wind turbine blade and the second wind turbineblade are arranged such that the maximum chord of the blades form anglesof between 15 and 35 degrees to a horizontal plane, advantageouslybetween 20 and 30 degrees, more advantageously around 25 degrees.

It is clear that all the embodiments described with respect to oneaspect of the invention also apply to any other aspect of the invention.

Advantageously, by providing the tip end frame with a base height h ontop of which the support bracket is located, this allows the base frameto be stacked on top of a preceding root end frame, such that thevertical height of the root end frame and the base frame of the tip endframe are substantially equal to the root end diameter of the supportedblade. The height of the tip end base frame is obviously lower than theentire height of the tip end transport frame h1 or h2.

Preferably, (0.5 D)<H<(0.9 D).

There is also provided a root end transport frame for a wind turbineblade, the blade having a tip end and a root end, the transport framehaving a height, a width, and a depth, wherein the height of thetransport frame is less than the bolt circle diameter of a root end of awind turbine blade to be supported by said transport frame.

A reduced-height transport frame allows for relatively easier handlingof the transport frame, and reduces transport and handling costs of theframe when not in use supporting a wind turbine blade.

Preferably, the width of said transport frame is equal to or greaterthan the bolt circle diameter of a wind turbine blade to be supported bysaid transport frame.

Preferably, the depth of said transport frame is equal to or greaterthan one quarter of the width of the transport frame.

Providing a transport frame with such dimensions results in a stablestructure with a low centre of mass, and which is able to support a windturbine blade.

Preferably, the root end transport frame comprises:

-   -   a frame body;    -   a root end plate coupled to said frame body, said root end plate        arranged to couple with a root end of a wind turbine blade,    -   wherein said root end plate is arranged to couple with less than        ⅔ of the bolt circle of a root end of a wind turbine blade to        support said wind turbine blade on said transport frame.

As the root end plate is designed to support a wind turbine blade byonly coupling with a portion of the root end of the wind turbine blade,accordingly the height of the root end plate relative to the bolt circlediameter of the root end of the wind turbine blade may be reduced,resulting in a reduced total height of the root end transport frame.

Preferably, said root end plate comprises a substantially C-shaped bodyarranged to couple with a portion of the bolt circle of a root end of awind turbine blade.

There is also provided a root end transport frame for a wind turbineblade, the blade having a tip end and a root end, the transport framecomprising:

-   -   a frame body; and    -   a root end plate for coupling to the root end of a wind turbine        blade, wherein said root end plate is hingedly coupled to said        frame body.

By providing a hinged root plate, any bending moments due to bladedeflection or bending are prevented from being transferred to the framebody. Accordingly, the frame body may be of a relatively lighterconstruction, as it does not need to bear such relatively large forces.

Preferably, said root plate is hingedly coupled to said frame body alongthe horizontal axis.

As the angle to the vertical made by the root end of a blade may dependon factors, such as the centre of gravity of the blade and the bladebending properties, accordingly the ability for the root plate to hingealong the horizontal axis allows for different angles of the blade rootend to be accommodated by the transport frame.

Additionally or alternatively, said root plate is hingedly coupled tosaid frame body along the vertical axis.

The hinging of the root plate around the vertical prevents damage to thetransport frame due to misalignment or handling issues.

Preferably, said root end plate is mounted on at least one bracket arm,said at least one arm coupled to said transport frame via a hingedjoint.

Preferably, said at least one bracket arm comprises an articulatedbracket.

The use of an articulated bracket allows for greater degrees of freedomof manipulation of the root plate, to more easily receive andaccommodate the root end of a wind turbine blade on the transport frame.

Preferably, said transport frame comprises at least a first and a secondbracket arm, wherein said first and second bracket arms are positionedon opposed sides of a notional central longitudinal axis of a windturbine blade to be mounted to said root end plate.

By positioning the bracket arms on either side of the centre point ofthe blade root end, the take up of forces from the root end of the bladeis balanced in the transport frame.

There is also provided a first tip end transport frame with a height h1for a wind turbine blade, the blade having a tip end and a root end, thetransport frame comprising:

-   -   a frame body;    -   a tip end support bracket for supporting a portion of a wind        turbine blade towards the tip end of said blade, wherein a first        end of said tip end support bracket is hingedly coupled to said        transport frame along the horizontal axis; and    -   wherein a leading edge support lip is provided on said bracket,        said leading edge support lip arranged to receive a portion of        the leading edge of a wind turbine blade supported by said        support bracket, such that the wind turbine blade can be        pivotably moved about said hinged coupling relative to said        transport frame while supported on said bracket.

There is also provided a second tip end transport frame with a height h2for a wind turbine blade, the blade having a tip end and a root end, thetransport frame comprising:

-   -   a frame body;    -   a tip end support bracket for supporting a portion of a wind        turbine blade towards the tip end of said blade, wherein a first        end of said tip end support bracket is hingedly coupled to said        transport frame along the horizontal axis; and    -   wherein a leading edge support lip is provided on said bracket,        said leading edge support lip arranged to receive a portion of        the leading edge of a wind turbine blade supported by said        support bracket, such that the wind turbine blade can be        pivotably moved about said hinged coupling relative to said        transport frame while supported on said bracket.

By providing a hinged coupling for the support bracket, a wind turbineblade may be adjusted relative to the frame body, to allow for correctpositioning of the wind turbine in the transport frame. The leading edgesupport lip provided on the bracket allows for the partial support ofthe wind turbine blade, preventing unwanted movement of the wind turbineblade during any such pivoting or subsequent transport.

Preferably, a second end of said support bracket may be releasablysecured to said frame body when said support bracket is received in saidframe body.

Preferably, said tip end support bracket comprises a flexible straphaving a support surface provided on said flexible strap.

The use of a flexible strap as part of the bracket allows for minoradjustments or movements of a supported wind turbine blade to beabsorbed through appropriate torsion or twisting of the strap, withoutbeing transferred to the relatively rigid frame body. Accordingly, theframe body may be of a more lightweight construction compared to priorart systems.

Preferably, the first and/or the second tip end transport frame furthercomprises a securing strap to be fitted around a wind turbine bladereceived in said transport frame.

Preferably, the tip end transport frame is arranged to be positioned ata location toward the tip end of a wind turbine blade to be supported bythe transport system, such that a sweep or bend of the wind turbineblade from the location of said tip end transport frame to the tip endof the supported blade is less than height h of the base frame of thetip end transport frame.

The transport system is preferably used in the transport of bladeshaving a pre-bend Δy, and/or swept blades. Accordingly, locating thesupport bracket of the tip end frame above the horizontal surface by aheight h allows for such a curved blade to be supported on the groundwithout the tip end of the blade striking the ground.

Preferably, the tip end transport frame is arranged to be positionedspaced from the tip end of the blade.

Preferably, a wind turbine blade to be supported by the transport systemhas a longitudinal length L, wherein the first or second tip endtransport frame is arranged to be positioned at a distance F from theroot end of said blade, wherein (0.5 L)<F<(0.95 L), preferably (0.6L)<F<(0.85 L).

Supporting the tip portion of the wind turbine blade at such a locationin the outboard portion of the blade, spaced from the tip end, providesa balance between effectively structurally supporting the blade, whilereducing the minimum effective wheelbase or support surface needed tosupport the total transport system.

It will be understood that any of the above-described features may becombined in any embodiment of the transport system as described.

DETAILED DESCRIPTION OF THE INVENTION

The invention is explained in detail below with reference to embodimentsshown in the drawings, in which

FIG. 1 shows a wind turbine,

FIG. 2 shows a schematic view of a wind turbine blade according to theinvention,

FIG. 3 shows a schematic view of an airfoil profile,

FIG. 4 shows a schematic view of the wind turbine blade according to anembodiment of the invention, seen from above and from the side,

FIG. 5 shows an embodiment of a root end transport frame according to anembodiment of the invention,

FIG. 6 shows an embodiment of a tip end transport frame according to anembodiment of the invention,

FIG. 7 shows a side view of an arrangement of wind turbine bladessupported by one embodiment of a modular system according to theinvention,

FIG. 8 shows a side view of an arrangement of wind turbine bladessupported by another embodiment of a modular system according to theinvention,

FIG. 9 shows a side view of an arrangement of wind turbine bladessupported by another embodiment of a modular system according to theinvention, and

FIG. 10 shows a cross-sectional view of an arrangement of wind turbineblades supported by an embodiment of a transport system according to theinvention.

The present invention relates to transport and storage of wind turbineblades for horizontal axis wind turbines (HAWTs).

FIG. 1 illustrates a conventional modern upwind wind turbine accordingto the so-called “Danish concept” with a tower 4, a nacelle 6 and arotor with a substantially horizontal rotor shaft. The rotor includes ahub 8 and three blades 10 extending radially from the hub 8, each havinga blade root 16 nearest the hub and a blade tip 14 furthest from the hub8. The rotor has a radius denoted R.

FIG. 2 shows a schematic view of a first embodiment of a wind turbineblade 10. The wind turbine blade 10 has the shape of a conventional windturbine blade and comprises a root region 30 closest to the hub, aprofiled or an airfoil region 34 furthest away from the hub and atransition region 32 between the root region 30 and the airfoil region34. The blade 10 comprises a leading edge 18 facing the direction ofrotation of the blade 10, when the blade is mounted on the hub, and atrailing edge 20 facing the opposite direction of the leading edge 18.

The airfoil region 34 (also called the profiled region) has an ideal oralmost ideal blade shape with respect to generating lift, whereas theroot region 30 due to structural considerations has a substantiallycircular or elliptical cross-section, which for instance makes it easierand safer to mount the blade 10 to the hub. The diameter (or the chord)of the root region 30 may be constant along the entire root area 30. Thetransition region 32 has a transitional profile gradually changing fromthe circular or elliptical shape of the root region 30 to the airfoilprofile of the airfoil region 34. The chord length of the transitionregion 32 typically increases with increasing distance r from the hub.The airfoil region 34 has an airfoil profile with a chord extendingbetween the leading edge 18 and the trailing edge 20 of the blade 10.The width of the chord decreases with increasing distance r from thehub.

A shoulder 40 of the blade 10 is defined as the position, where theblade 10 has its largest chord length. The shoulder 40 is typicallyprovided at the boundary between the transition region 32 and theairfoil region 34.

It should be noted that the chords of different sections of the bladenormally do not lie in a common plane, since the blade may be twistedand/or curved (i.e. pre-bent), thus providing the chord plane with acorrespondingly twisted and/or curved course, this being most often thecase in order to compensate for the local velocity of the blade beingdependent on the radius from the hub.

The wind turbine blade 10 comprises a shell made of fibre-reinforcedpolymer and is typically made as a pressure side or upwind shell part 24and a suction side or downwind shell part 26 that are glued togetheralong bond lines 28 extending along the trailing edge 20 and the leadingedge 18 of the blade 10.

FIGS. 3 and 4 depict parameters, which are used to explain the geometryof the wind turbine blades to be stored and transported according to theinvention.

FIG. 3 shows a schematic view of an airfoil profile 50 of a typicalblade of a wind turbine depicted with the various parameters, which aretypically used to define the geometrical shape of an airfoil. Theairfoil profile 50 has a pressure side 52 and a suction side 54, whichduring use—i.e. during rotation of the rotor—normally face towards thewindward (or upwind) side and the leeward (or downwind) side,respectively. The airfoil 50 has a chord 60 with a chord length cextending between a leading edge 56 and a trailing edge 58 of the blade.The airfoil 50 has a thickness t, which is defined as the distancebetween the pressure side 52 and the suction side 54. The thickness t ofthe airfoil varies along the chord 60. The deviation from a symmetricalprofile is given by a camber line 62, which is a median line through theairfoil profile 50. The median line can be found by drawing inscribedcircles from the leading edge 56 to the trailing edge 58. The medianline follows the centres of these inscribed circles and the deviation ordistance from the chord 60 is called the camber f. The asymmetry canalso be defined by use of parameters called the upper camber (or suctionside camber) and lower camber (or pressure side camber), which aredefined as the distances from the chord 60 and the suction side 54 andpressure side 52, respectively.

Airfoil profiles are often characterised by the following parameters:the chord length c, the maximum camber f, the position d_(f) of themaximum camber f, the maximum airfoil thickness t, which is the largestdiameter of the inscribed circles along the median camber line 62, theposition d_(t) of the maximum thickness t, and a nose radius (notshown). These parameters are typically defined as ratios to the chordlength c. Thus, a local relative blade thickness t/c is given as theratio between the local maximum thickness t and the local chord lengthc. Further, the position d_(p) of the maximum pressure side camber maybe used as a design parameter, and of course also the position of themaximum suction side camber.

FIG. 4 shows other geometric parameters of the blade. The blade has atotal blade length L. As shown in FIG. 3, the root end is located atposition r=0, and the tip end located at r=L. The shoulder 40 of theblade is located at a position r=L_(w), and has a shoulder width W,which equals the chord length at the shoulder 40. The diameter of theroot is defined as X. Further, the blade is provided with a prebend,which is defined as Δy, which corresponds to the out of plane deflectionfrom a pitch axis 22 of the blade.

Blades have over the time become longer and longer and may now exceed alength of 70 metres. The length of the blades as well as the shape ofthe blades with respect to shoulder, twist and prebending makes itincreasingly difficult to transport the blades, in particular if aplurality of blades is to be transported and stored together. The shapeand size of the blades also puts limitations on how closely the bladescan be stored in a stacked array.

With reference to FIG. 5, an embodiment of a root end transport frameaccording to an aspect of the invention is indicated generally at 100.The root end transport frame 100 comprises a frame body 102 and a rootend plate 104 coupled to the frame body 102. FIG. 5(a) illustrates afront perspective view of the transport frame 100, FIG. 5(b) illustratesa plan view of a root end plate 104 of the transport frame, FIG. 5(c)illustrates a rear perspective view of the transport frame 100, and FIG.5(d) illustrates a rear perspective view of the root end plate of theframe of FIG. 5(c).

The transport frame 100 is arranged to couple with less than the entirecircumference of a bolt circle of a wind turbine blade to be supportedby the transport frame, as this provides several advantages in terms ofstability, and transport and handling issues.

The transport frame 100 is designed to have a height H less that thebolt circle diameter of the root end of a wind turbine blade to besupported by the transport frame, and preferably to have a width Wgreater than or equal to said bolt circle diameter. The depth D_(f) ofthe frame 100 is designed to adequately support the frame 100,preferably being at least one quarter of the bolt circle diameterdistance. Such a construction provides a relatively low centre of massof the transport frame 100, and reduced the possibility of the frame 100being easily overturned, either when supporting a root end of a windturbine blade or when not supporting a blade.

The root end plate 104 is hingedly coupled to the frame body 102, via apair of projecting bracket arms 106. In the embodiment of FIG. 5, thebracket arms 106 are hinged to the frame body 102 about the horizontalaxis, but it will be understood that any suitable hinged joint may beprovided, and/or articulated brackets may be provided. The use of ahinged connection between the root end plate 104 and the frame body 102means that the plate 104 can be provided at any suitable angle to thevertical, to accommodate any bending or deflection of the root end ofthe wind turbine blade, without transferring such bending moments to theframe body 102. As a result, the frame body 102 may be of a relativelylightweight construction, as it does not have to bear such relativelylarge bending moments from the blade root end.

Preferably, at least two bracket arms 106 are provided, with the arms106 arranged to be spaced around the centre point of the root end of ablade supported by said transport frame 100, such that the forcesassociated with said wind turbine blade are evenly transferred to thesupporting frame body 102.

The root end plate 104 is preferably arranged to couple with asubsection of the bolt circle of a wind turbine blade root end,resulting in a reduced height of the total structure of the transportframe 100. The embodiment of FIG. 5 shows the end plate 104 having asubstantially C-shaped structure, wherein the plate 104 is operable tocouple with approximately ⅔ of the bolt circle of a wind turbine bladeroot end. The shape and coupling of the root end plate 104 is selectedso as to adequately support a root end of a wind turbine blade, whilekeeping the height of the transport frame 100 structure to a minimum.

It will be understood that any other suitable shape of root end plate104 may be used, which is arranged to couple with a portion of a boltcircle of a wind turbine blade, e.g. a U-shaped plate, a substantiallysquare plate, etc.

It will be understood that the root end plate 104 may be provided with aplurality of coupling apertures arranged along separate notional boltcircles on the end plate 104, to accommodate the coupling of the rootend plate 104 to root ends of different wind turbine blades havingdifferent bolt circle diameters. This allows the root end transportframe 100 to be interchangeably used with wind turbine blades ofdifferent dimensions. It will further be understood that the couplingapertures may be shaped to be wider and/or longer than correspondingapertures in the bolt circle of a wind turbine blade, to allow foradjustment of coupling between the root end plate 104 and the blade rootend, for example in the event of misalignment, root end ovalisation,etc.

With reference to FIG. 6(a), an embodiment of a tip end transport frameaccording to an aspect of the invention is indicated generally at 108.The transport frame 108 comprises a base frame 110 and a support portion112 provided at the top of the base frame 110. The support portion 112comprises at least one tip end support bracket 114 which is hingedlycoupled to the transport frame 108. The support bracket 114 receives aportion of a wind turbine blade (indicated by section 116) to besupported by the tip end transport frame 108, wherein the blade portionis spaced from the tip end of the blade.

With reference to FIG. 6(b), an enlarged view is shown of an example ofa tip end support bracket 114. The bracket 114 comprises first andsecond ends 118 a,118 b arranged to couple with the support portion 112of the tip end transport frame 108. The bracket 114 further comprises acushioning or padding material 120 arranged to support the surface of awind turbine blade. A leading edge support lip 122 is provided on thebracket 114, preferably projecting from the cushioning or paddingmaterial 120. The leading edge support lip 122 is arranged to receivethe leading edge of a wind turbine blade supported on the bracket 114,to prevent movement of the blade when on the bracket 114.

In use, a first end 118 a of the bracket 114 may be attached to thesupport portion 112, with the second end 118 b projecting free of theframe. A portion 116 of a wind turbine blade can be placed on thebracket 114 with the leading edge of the blade fitted adjacent to saidlip 122. The bracket may then be pivoted relative to the transport framebody, to position the blade within the transport frame 108, at whichpoint the second end 118 b of the bracket 114 can be secured to theframe 108. A secondary support strap 124 may then be positioned over thesurface of the blade section 116 opposed the support bracket 114, andsecured to the support portion 112, to securely retain the wind turbineblade within the transport frame 108.

It will be understood that the support bracket 114 may be formed from arelatively flexible strap having a cushioning or padding material 120and a leading edge support lip 122 moulded onto the strap.

The base frame 110 of the tip end transport frame 108 has a height h.This ensures that the portion 116 of the wind turbine blade is supportedat a distance h from the ground or underlying surface. With reference toFIG. 13, this configuration of a transport system for a wind turbineblade provides additional advantages when used for the transportation orstorage of pre-bent wind turbine blades, where the wind turbine bladesare manufactured to have a curve or bend in a substantially upwinddirection, as described in European Patent No. EP1019631.

FIG. 7 is a schematic side view of a first embodiment of a modularsystem 200 according to the present invention. The modular systemcomprises two root end transport frames 171, 271 each having a height H,two first tip end transport frames 172, 272 each having a height h1, andtwo second tip end transport frames 372, 472 each having a height h2exceeding h1. In FIG. 7(a), the first tip end transport frame 172 isattached on top of root end transport frame 171 at one end, and root endtransport frame 271 is attached on top of the other tip end transportframe 272 at the opposing end. Accordingly, two wind turbine blades 10are vertically stacked in a root end to tip end arrangement, each beingsupported by one root end transport frame and one tip end transportframe. Two second tip end transport frames 372, 472 are also part of themodular system of this embodiment but are not displayed in use in FIG.7(a).

FIG. 7(b) shows the same modular system 200 as in FIG. 7(a), however,here the second tip end transport frames 372, 472 are used instead ofthe first tip end transport frames 172, 272 to increase the inter-bladespacing during transport.

The configuration with lower inter-blade spacing may for instance beused during land transport or storage. Further, intermediate supportmeans (not shown) may be arranged between the blades in order to providea cushion effect and protect the blades. The configuration with largerinter-blade spacing may for instance be used for sea transport, wherethe frame system and blades may be subject to turbulence from the sea.

FIG. 8 is a schematic side view of another embodiment of the modularsystem 200 according to the present invention. The modular systemcomprises two root end transport frames 171, 271 each having a height H,two first tip end transport frames 172, 272 each having a height h1, andtwo tip end extension pieces 201, 202. In FIG. 8(a), the first tip endtransport frame 172 is attached on top of the root end transport frame171 at one end, while the root end transport frame 271 is attached ontop of the other tip end transport frame 272 at the opposing end. InFIG. 8(a), the tip end extension pieces are not used. By contrast, inFIG. 8(b) the extension piece 201 is attached below the first tip endtransport frame 172, and the extension piece 202 is attached below thefirst tip end transport frame 272 to increase the inter-blade spacing ascompared to the arrangement of FIG. 8(a).

While the modular system 200 has been described as a system, where anextension piece 201, 202 is attached to the tip end transport frame 172,272, it is also recognised that a similar technical effect can beachieved by providing a tip end frame, which has a removable extensionpiece. This is illustrated in FIGS. 8c and 8d , where FIG. 8c shows atip end transport frame 172 and a removable extension piece or distancepiece 201 (corresponding to the transport or storage shown in FIG. 8b ),whereas FIG. 8d shows the tip end transport frame 172 with the removableextension piece 201 removed (corresponding to the transport or storageshown in FIG. 8a ). The removable extension piece 201 may for instancehave a height of 20-40 cm.

FIG. 9 is a schematic side view of yet another embodiment of the modularsystem 200 according to the present invention. Again, the modular system200 comprises two root end transport frames 171, 271 each having aheight H, two first tip end transport frames 172, 272 each having aheight h1, and two tip end extension pieces 201, 202. In FIG. 9(a), thefirst tip end transport frame 172 is attached on top of the root endtransport frame 171 at one end, while the root end transport frame 271is attached on top of the other tip end transport frame 272 at theopposing end. Also shown in FIG. 9(a) is a root end extension piece 203having a height h3. In FIG. 9(b), the root end extension piece isinserted in the stack by attaching it in between the two verticallystacked root end transport frames 171, 271. This enables an alternativespatial arrangement in that the blades 10 can now be stacked in a rootend to root end fashion, thus reducing overall stack length andsimultaneously minimising the inter-blade spacing.

FIG. 10 is a cross-sectional view of a transport system 300 according tothe present invention. The transport system 300 comprises two root endtransport frames 171, 271 each having a height H and two extendible tipend transport frames 572, 672. Two wind turbine blades 10 are supportedby the transport frames in a root end to tip end vertical stack. Eachextendible tip end transport frame 572, 672 contain a threaded leg 204,205 which is received in bore or a fixture with a matching internalthread within the respective transport frame. In FIG. 10(a) the legs204, 205 are shown in a retracted position for reduced inter-bladespacing. In FIG. 10(b), the legs 204, 205 are shown in an extendedposition to increase the overall height of the tip end transport frames572, 672, thereby increasing inter-blade spacing, e.g. for seatransport.

The invention has been described with reference to preferredembodiments. However, the scope of the invention is not limited to theillustrated embodiments, and alterations and modifications can becarried out without deviating from the scope of the invention that isdefined by the following claims.

The invention is not limited to the embodiments described herein, andmay be modified or adapted without departing from the scope of thepresent invention.

LIST OF REFERENCE NUMERALS

-   2 wind turbine-   4 tower-   6 nacelle-   8 hub-   10 blade-   14 blade tip-   15 tip end section-   16 blade root-   17 root end face-   18 leading edge-   20 trailing edge-   22 pitch axis-   24 pressure side shell part/upwind shell part-   26 suction side shell part/downwind shell part-   28 bond lines-   29 horizontal-   30 root region-   32 transition region-   34 airfoil region-   50 airfoil profile-   52 pressure side/upwind side-   54 suction side/downwind side-   56 leading edge-   58 trailing edge-   60 chord-   62 camber line/median line-   100 root end transport frame-   102 frame body-   104 root end plate-   106 bracket arms-   108 tip end transport frame-   110 base frame-   112 support portion-   114 support bracket-   116 wind turbine blade portion-   118 support bracket end-   120 cushioned support material-   122 leading edge support lip-   124 retaining strap-   171 root end transport frame-   172 first tip end transport frame-   200 modular system-   201 tip end extension piece-   202 tip end extension piece-   203 root end extension piece-   204 threaded leg-   205 threaded leg-   271 root end transport frame-   272 first tip end transport frame-   300 transport system-   372 second tip end transport frame-   472 second tip end transport frame-   572 extendible tip end transport frame-   672 extendible tip end transport frame-   c chord length-   d_(t) position of maximum thickness-   d_(f) position of maximum camber-   d_(p) position of maximum pressure side camber-   f camber-   L blade length-   r local radius, radial distance from blade root-   t thickness-   D blade root diameter-   Δy prebend-   H root end transport frame height-   W root end transport frame width-   D_(f) root end transport frame depth-   h tip end base frame height-   h1 height of first tip end transport frame-   h2 height of second tip end transport frame-   h3 height of root end distance piece

1-22. (canceled)
 23. A transport system for transporting wind turbineblades in at least two different spatial arrangements, each blade havinga tip end and a root end, each blade further having a bolt circlediameter D at said root end, the system comprising: two or more root endtransport frames each having a height H for supporting a root end of awind turbine blade, wherein H<D; two or more extendible tip endtransport frames for supporting a portion of a wind turbine bladetowards the tip end of said blade, each extendible tip end transportframe comprising a base frame, at least one vertical extension means forextending the height of the tip end transport frame and a supportbracket provided on top of said base frame for receiving a portion of awind turbine blade; wherein each extendible tip end transport frame isstackable on top of a root end transport frame and vice versa, such thatthe modular system is operable to stack successive wind turbine bladesin an alternating root end to tip end arrangement with at least twoalternative inter-blade spacings created by varying the height of theextendible tip end transport frames via the vertical extension means.24. The transport system of claim 23, wherein the vertical extensionmeans are suitable for extending the height of the tip end transportframe stagelessly.
 25. The transport system of claim 23, wherein thevertical extension means consists of one or more threaded legs suitablefor continuous height adjustment and at least partially received in thebase frame of the extendible tip end transport frame.